This invention relates generally to paste material dispensing devices and particularly to a system for unformly dispensing frit material to a seal edge of a funnel portion of a CRT (cathode ray tube).
A CRT envelope is composed of a faceplate panel and a funnel portion. A phosphor screen is provided on the inside surface of the faceplate panel and luminesces when impacted by electrons to produce a visual output. The funnel portion includes a neck to support the electron gun which provides the electrons to scan the phosphor screen. The funnel portion and faceplate panel must be permanently and hermetically joined to permit evacuation of the envelope as required for operation of the CRT. The panel and funnel are each provided with mating seal edges along which they are joined. A vitrifiable material is placed continuously along one of the seal edges. The funnel is placed in a carrier and the panel is placed in the funnel with the mating seal edges aligned. The carrier supports the funnel and panel as they pass through an oven which is raised to high temperature to vitrify the frit material to permanently and hermetically join the two components.
Typically the frit material is applied to the sealing edge of the funnel by rotating the funnel at a constant rotating speed. A frit material dispenser is pivotably arranged above the seal edge and the uniform dispensation of the frit material requires the dispenser to remain a constant distance from the funnel as the funnel rotates. The dispenser includes a follower to retain the dispenser above the seal edge as the funnel rotates. For these reasons, it is important for the seal edge to be located in a reference plane and to be properly oriented and centered with respect to the outlet orifice of the dispenser. The present invention fulfills these important requirements.